Devices with a passageway for electroosmotic flow and method of making same

Abstract

A device has a passageway ( 14 ) for electroosmotic flow therealong. The passageway ( 14 ) is bordered by an internal surface ( 12 ). A porous plug ( 16,18 ) is located in the passageway ( 14 ) so that there are no gaps between the porous plug ( 16, 18 ) and the internal surface ( 12 ). The plug ( 16,18 ) is made by curing a paste comprising a filler, such as glass powder, and a silicate solution. The passageway preferably has a maximum cross-sectional dimension of greater than 500 μm, a minimum cross-sectional dimension of greater than 500 μm or a cross-sectional area of greater than 0.2 mm 2 .

1 . A method of making a device for electroosmotic flow therein, comprising, preparing a device with a passageway therein and with a porous plug in the passageway, the porous plug being formed by curing a paste comprising filler particles and a silicate solution, the device having an internal surface which borders the passageway and which is contacted by the plug all around the passageway without any gaps therein.  
   
   
       2 . A method according to  claim 1 , wherein the filler particles are glass powder.  
   
   
       3 . A method according to  claim 2 , wherein the filler particles are borosilicate glass powder.  
   
   
       4 . A method according to  claim 1 , wherein the particles have a surface charge when in an electroosmotic liquid.  
   
   
       5 . A method according to  claim 1 , wherein the particles have a diameter of from 1 μm to 20 μm.  
   
   
       6 . A method according to  claim 5 , wherein the particles have a diameter from 2.5 μm to 10 μm.  
   
   
       7 . A method according to  claim 1 , wherein the silicate solution is a potassium silicate solution or a sodium silicate solution.  
   
   
       8 . A method according to  claim 7 , wherein the silicate solution is a solution of SiO 2  and K 2 O.  
   
   
       9 . A method according to  claim 1 , including curing the paste by heating.  
   
   
       10 . A method according to  claim 1 , wherein the proportion of the filler particles to the silicate solution is greater than 1:1 by volume.  
   
   
       11 . A method according to  claim 10 , wherein the proportion is about 2:1 by volume.  
   
   
       12 . A method according to  claim 1 , wherein the passageway has a maximum cross-sectional dimension of greater than 500 μm, or greater than 600 μm, or greater than 700 μm, or greater than 800 μm, or greater than 900 μm, or greater than 1000 μm or greater than 1200 μm, or greater than 1400 μm, or greater than 1600 μm, or greater than 1800 μm, or greater than 2000 μm.  
   
   
       13 . A method according to  claim 1 , wherein the passageway has a minimum cross-sectional dimension of greater than 500 μm, or greater than 600 μm, or greater than 700 μm, or greater than 800 μm, or greater than 900 μm, or greater than 1000 μm, or greater than 1200 μm, or greater than 1400 μm, or greater than 1600 μm, or greater than 1800 μm, or greater than 2000 μm.  
   
   
       14 . A method according to  claim 1 , wherein the passageway has a cross-sectional area of greater than 0.2 mm 2 , or greater than 0.3 mm 2 , or greater than 0.4 mm 2 , or greater than 0.5 mm 2 .  
   
   
       15 . A method according to  claim 1 , wherein preparing the device comprises providing a tube having a passageway, positioning the paste in the passageway and curing the paste in the passageway.  
   
   
       16 . A method according to  claim 1 , wherein preparing the device comprises providing a first member with a groove and a second member with a member surface, attaching the members to one another so that the member surface closes the groove to form said passageway.  
   
   
       17 . A device with a passageway for electroosmotic flow therein, the device having an internal surface which borders the passageway, a porous plug within the passageway, the plug contacting the surface all around the passageway without any gaps therebetween.  
   
   
       18 . A device according to  claim 17 , wherein the porous plug comprises filler particles bound together by silica.  
   
   
       19 . A device according to  claim 18 , wherein the filler particles are glass particles.  
   
   
       20 . A device according to  claim 19 , wherein the filler particles are borosilicate glass particles.  
   
   
       21 . A device according to  claim 18 , wherein the particles have a surface charge when in an electroosmotic environment.  
   
   
       22 . A device according to  claim 18 , wherein the particles have a diameter of from 1 μm to 20 μm.  
   
   
       23 . A device according to  claim 22 , wherein the filler particles have a diameter of from 2.5 μm to 10 μm.  
   
   
       24 . A device according to  claim 17 , wherein the passageway has a maximum cross-sectional dimension of greater than 500 μm, or greater than 600 μm, or greater than 700 μm, or greater than 800 μm, or greater than 900 μm, or greater than 1000 μm, or greater than 1200 μm, or greater than 1400 μm, or greater than 1600 μm, or greater than 1800 μm, or greater than 2000 μm.  
   
   
       25 . A device according to  claim 17 , wherein the passageway has a minimum cross-sectional dimension of greater than 500 μm, or greater than 600 μm, or greater than 700 μm, or greater than 800 μm, or greater than 900 μm, or greater than 1000 μm, or greater than 1200 μm, or greater than 1400 μm, or greater than 1600 μm, or greater than 1800 μm, or greater than 2000 μm.  
   
   
       26 . A device according to  claim 17 , wherein the passageway has a cross-sectional area of greater than 0.2 mm 2 , or greater than 0.3 mm 2 , or greater than 0.4 mm 2 , or greater than 0.5 mm 2 .  
   
   
       27 . A device according to  claim 17 , wherein the passageway is formed in a tube.  
   
   
       28 . A device according to  claim 17 , wherein the device comprises a first member having a groove and a second member having a member surface, the members being attached to one another so that the member surface closes the groove to form the passageway.  
   
   
       29 . A device according to  claim 17 , wherein the device has a second porous plug in the passageway, a supported catalyst or supported reagent being provided in the passageway and being held between the two porous plugs.  
   
   
       30 . A method of generating electroosmotic flow comprising, providing a device with a passageway for electroosmotic flow therein, the device having an internal surface which borders the passageway, a porous plug within the passageway, the plug contacting the surface all around the passageway without any gaps therebetween, the method also comprising filling the passageway and the pores of the or each porous plug with a liquid, and applying an electric voltage across the length of the passageway to cause electroosmotic flow therealong.  
   
   
       31 . A method according to  claim 30 , wherein the device has a second porous plug in the passageway, a supported catalyst being provided in the passageway and being held between the two porous plugs, wherein the supported catalyst is an acid catalyst and the liquid is a solution comprising a dithiol and either an aldehyde or a ketone.  
   
   
       32 . A method according to  claim 31 , wherein the solution is a solution in acetonitrile.  
   
   
       33 . A method according to  claim 31 , wherein the supported catalyst is Amberlyst-15.  
   
   
       34 . A method according to  claim 31 , wherein there is a third porous plug in the passageway, the supported catalyst being held between the first mentioned and second plugs and a scavenger being held between the second and third porous plugs, the scavenger being downstream of the supported catalyst in the direction of electroosmotic flow and the scavenger removing any unreacted dithiol from the solution.  
   
   
       35 . A method according to  claim 34 , wherein the scavenger is silica supported copper sulphate.  
   
   
       36 . A method according to  claim 30 , wherein the device has a second porous plug in the passageway, a supported catalyst or supported reagent being provided in the passageway and being held between the two porous plugs, wherein a supported organic base is held between the first mentioned and second porous plugs, and the solution comprises an aldehyde and an activated methylene.  
   
   
       37 . A method according to  claim 36 , wherein the solution is a solution in acetonitrile.  
   
   
       38 . A method according to  claim 36 , wherein the supported organic base is a primary or secondary amine.  
   
   
       39 . A method according to  claim 38 , wherein the supported organic base is silica supported piperazine.  
   
   
       40 . A method according to  claim 30 , wherein the device has a second porous plug in the passageway, a supported catalyst or supported reagent being provided in the passageway and being held between the two porous plugs, wherein there is a third porous plug in the passageway, the first mentioned supported catalyst or reagent being held between the first mentioned and second porous plugs and a second supported catalyst or reagent being held between the second and third porous plugs, the first supported catalyst or reagent being upstream and the second supported catalyst or reagent being downstream in the direction of electroosmotic flow, sequential reactions taking place between the first mentioned and second porous plugs and between the second and third porous plugs.  
   
   
       41 . A method according to  claim 40 , wherein the first mentioned supported catalyst or reagent is an acid catalyst and the second supported catalyst or reagent is an organic base, a solution of a dimethyl acetal and a activated methylene group passing along the passageway with the dimethyl acetal being converted to an aldehyde by the supported acid catalyst and the aldehyde reacting with the activated methylene to form an α, β-unsaturated compound between the second and third porous plugs.  
   
   
       42 . A method of preparing a 1,3-dithiane or a 1,2-dithiolane, comprising mixing an aldehyde or a ketone with a dithiol and passing the mixture through a supported acid catalyst so as to produce a 1,3-dithiane or a 1,2-dithiolane.  
   
   
       43 . A method according to  claim 42 , wherein the supported acid catalyst is Amberlyst-15.  
   
   
       44 . A method according to  claim 42 , wherein the mixture is passed through the supported acid catalyst by electroosmotic force.  
   
   
       45 . A method according to  claim 44 , wherein the mixture is a solution in acetonitrile.  
   
   
       46 . A method according to  claim 30 , wherein the porous plug comprises filler particles bound together by silica.